Is Kombucha Healthy? A general introduction.

Simply Kombucha

The following article is adapted from the ‘Health Claims’ chapter in my book Simply Kombucha.


Kombucha has a long history of being promoted as a health drink. Almost every blog or article I read about kombucha has a list of medical complaints or illnesses that it is supposed to heal or at least help with.

All the early kombucha books from the 1990s are full of hints and tips about using kombucha to heal wounds, beat arthritis, or combat hair-loss. Even AIDS was claimed to respond to this amazing “miracle mushroom”.
On closer reading I found that the authors of those books also tended to speculate about cosmic rays and crop circles, making me a touch skeptical about their medical opinions, no matter how expert they were in the art of brewing kombucha. So I looked online to see what the current state of opinion was about kombucha’s healing powers.

I came across many Internet sites and blogs making big promises about kombucha’s health benefits. I saw claims that it can cure everything from skin complaints to cancer to diabetes. So many people reported feeling better after drinking kombucha, or that they had seen a reversal of some troubling symptoms that I was encouraged.

But on the other hand, many of the claims appeared to have just been copied and pasted from one site to another in a giant game of telephone, and none of them could be independently verified. The kombucha sites that claimed “scientific research” didn’t actually link to the research itself — it all appeared to be done by nameless Soviet scientists, or the mysterious generic “researchers” of the phrase “researchers have found…”

It all appeared to be a giant echo chamber of the same information bounced back and forth between sites, with no clue as to where it originally came from or how reliable it ultimately was.

I began to doubt that there was any underlying truth at all to the health claims about kombucha.

Fortunately, when I turned to the scientific literature itself I found that scientists really are doing research on kombucha. The last time I checked I found over seventy publications in scientific journals since 1990, eleven of those from 2015 alone. Since then I’ve been slowly working my way through those articles to find out exactly what is, and is not, currently known about kombucha

And I’ve been thanking my lucky stars for that Masters degree in Biochemistry. Whoever knew just how useful it would turn out to be?!

So, just what is it that we do know?

It seems pretty clear from the research that kombucha is both a powerful antioxidant and a useful probiotic. The research is still in its early days, so no conclusions can yet be reached about using kombucha as a therapy to treat human diseases, but the initial results are promising.

There are research groups around the globe investigating kombucha’s impact on diabetes, heart disease, and liver and kidney health. Other groups are investigating whether and how it might protect against damage from industrial chemicals, pollution, and radiation. Still others are investigating its usefulness as a probiotic or medically functional food and whether a kombucha scoby can be used to enhance drinks other than tea.

Because the research into specific human diseases and the impact kombucha has on them is in its very early stages I’m not going to get into that level of detail here. Suffice it to say that it is too early to tell what, if any, specific therapeutic uses kombucha may have.

So what I’ll do is focus the discussion on kombucha’s antioxidant and probiotic properties, both of which are fairly well established in the scientific literature.

Kombucha is an antioxidant

So, just what is an antioxidant when it’s at home?

To answer that question, we need to back up just a fraction and talk about free radicals and oxidative stress.

Under normal, healthy conditions our bodies beaver away busily digesting food, repairing cells, duplicating DNA, healing wounds, fighting off infection and all manner of other amazing things. In the process of doing all this work, the molecular interactions that take place often produce waste products – the same way that when we’re cooking a fantastic meal in our kitchens we are left with carrot ends, potato peels, empty spice packets and other bits and pieces for the compost heap or recycling bins.

One type of molecular waste product that the body produces is a free radical. The majority of free radicals that the body makes are called Reactive Oxygen Species. Now, normally Oxygen is a good thing and we need it. But sometimes the hard work going on inside the body leaves an oxygen molecule hanging around with too many electrons. This is a bad thing.

The oxygen with too many electrons is very unstable and, if I can describe it as if it had feelings, is desperate to unload those electrons wherever it can, so it can get back to its normal, stable self. And so it does unload those electrons — often onto molecules that then become highly unstable themselves.

A chain reaction can begin where these highly reactive molecules, these free radicals, will react with any molecule they bump into. Often these reactions change the function, the shape, and the behavior of the molecules. If free radicals were left unchecked in your body, you would get into a state of what is called oxidative stress. Oxidative stress can lead to a number of different diseases including cancer and cardiovascular disease, depending on which molecules are affected.

Fortunately, a normal healthy body has a front line defense system set up to mop up and dispose of free radicals before they can do much damage. The key defense mechanism is the use of antioxidants. The body makes a number of different antioxidants, which are effective in different parts of the cell and outside of the cells too.

So, not to worry, right?

The body has it under control, right?

Well, not so much. You see we encounter a number of free radicals in our daily lives as well, and the more we encounter the harder it is for our body to keep up with neutralizing them and getting rid of them. Additional free radicals are produced by the body when fighting off an infection or inflammation. Industrial pollutants often contain free radicals, as does smoke, tobacco, drugs, some medications, radiation and some solvents.

Infographic: Antioxidants, Free Radicals, and Oxidative Stress

Most of us come into contact with some or all of these sources of free radicals every day. If your body isn’t producing sufficient antioxidant activity to counteract all these free radicals then you can find yourself in a state of oxidative stress, even if your body is in tip-top condition.
In order to try to combat these free radicals that are coming in from outside the body, we can make sure we are getting a good supply of antioxidants.

There are two main sources of antioxidants — synthetic ones and natural ones. Synthetic antioxidants have been used in the food industry for a while as they help prevent spoilage and increase shelf-life. More recently, though, they have been demonstrated to be toxic in large doses, so they’re probably best avoided if your goal is to be healthier and live longer.

Fresh fruit and veg contain antioxidants

In contrast, natural antioxidants such as flavonoids and polyphenols are found in good quantities in fresh fruit and vegetables. These antioxidants are thought to be one of the reasons why people who eat a diet high in fresh veggies have better health outcomes than those who don’t. In particular, ordinary green or black tea has had a lot of attention paid to it because it has a very high level of polyphenols in it. Green tea has more of them than black tea.

And it turns out that kombucha — the fermented version of those green or black teas — has even more polyphenols, and a wider variety of them, than the plain tea does.

So. If I can briefly re-cap, the story so far is that antioxidants in the body help neutralize free radicals, but many of us encounter more free radicals than our body can naturally cope with. This situation is called oxidative stress, and can lead to a variety of health problems. We know that kombucha has a high level of antioxidants in it. The question then remains — does drinking kombucha actually help us combat those antioxidants?

The likely answer is yes. Dr Gharib at Cairo’s National Centre for Radiation Research and Technology, and Dr Aloulou and his colleagues at the University of Sfax in Tunisia have each published some fascinating research papers in the last few years. Each research team demonstrated that rats who had regularly been drinking kombucha were protected from the toxic effects of free radicals.

Now, I won’t get into too many details, because laboratory experimentation on animals does not generally make for happy reading. But basically they took some rats and fed some of them with kombucha for several weeks — an equivalent dose to a human drinking half a cup per day. After that time they exposed the rats to a toxic amount of a free radical and then examined the rats.

Rats which drank kombucha were protected from toxic free radicals

The rats that had been dosed with kombucha were significantly healthier than those who had been on a normal lab-rat diet.

These research results are highly promising, and although nothing is known for certain about how kombucha might act as an antioxidant in humans, I personally find the results compelling enough that I make kombucha part of my daily diet.

Of course, it helps that it is delicious too.

Kombucha is a probiotic

As well as being a good antioxidant, kombucha is often hailed as being a probiotic. But just what are probiotics and why do you want them?

Well, a healthy body has got a lot of microbes living in it and on it. Humans are basically walking colonies of microbial life.

The most important microbes for our health live in our gut — this is what we call our gut flora or intestinal flora. We rely on these microbes to help us digest our food for us. It’s teamwork in a way — they digest some of the things that we find difficult to break down, making it easy for us to absorb the nutrients, and in turn we provide them with a constant supply of food. They also help protect us from “bad” bacteria and can be thought of as part of our immune system.

If your gut environment gets disturbed or disrupted then the community of microbes in your gut can get out of balance, which can mean that some of those vital digesting-type processes don’t happen properly.
Think of your gut as being like a tropical jungle, a tidal estuary, or some other complex ecosystem. There are lots of different animals and plants living there, all hopefully in balance, all keeping the jungle or estuary operating as it should — producing oxygen, increasing soil fertility, supporting life in abundance.

Now think of what happens in those places when there is a disaster of some sort — either a natural disaster like a mud slide or forest fire, or a human-created disaster like over-fishing of particular species or clearing trees to convert into pasture. The system gets out of balance. There is often a chain reaction of effects and unintended consequences, and the jungle or estuary is no longer working as well or effectively as it was before.

The complex community in your gut can also get out of balance and stop working at its best. This is sometimes called gut dysbiosis. Some recorded causes of gut dysbiosis are prolonged or inappropriate use of antibiotics, not eating a good variety of foods (starving some of your good bacteria and over-feeding some of the others) and alcohol misuse. It is worth noting too, that newborn babies have got a sterile gut, so all humans need to acquire our gut bacteria from our food and environment — it’s not something that just magically happens. Perhaps this is the origin of the old wives’ tale that babies need to eat a peck of dirt to be healthy.
In this very industrial day and age where not many people have daily contact with soil and much of what we eat is sterile, highly refined and processed, it is entirely likely that some of us have never acquired a good, broad mix of healthy gut microbes.

The easiest way to address an out-of-whack gut situation is with probiotics.

Naturally fermented sauerkraut is probiotic.

Probiotics are foods or drinks that contain live healthy cultures of microbes that are good for your gut. Many of these you’ll already be aware of, and some are integral parts of delicious international dishes. Natural yoghurt, raw cheeses, Korean kimchi, naturally fermented sauerkraut, Central American curtido, Indian lassi, Eastern European milk kefir, and of course kombucha are all probiotics. Basically anything that is naturally fermented or pickled and involves lactic-acid fermentation is a probiotic.

Just as an aside, the types of fermentation that are yeast-based and produce mostly alcohol are not probiotic. A lot of alcohol tends to kill microbes so is not good for your gut, and too much yeast can cause problems for some people.

Probiotics are available in capsule form as health supplements, but by far the easiest way to ingest probiotics is to eat a variety of naturally fermented foods.

Each type of probiotic food will have its own mix of microbes. The microbes in yoghurt will be different to those in kimchi. In fact each person’s culture or brew, and each different recipe will also result in a unique mix of microbes — so my kombucha will be different to yours. In order to get a good variety of probiotic microbes into your gut it is a good idea to eat a range of probiotic foods in your diet.

A couple of studies have looked into the probiotic properties of kombucha. (I summarize one of them here). They found a wide variety of beneficial bacteria and yeast, and also found that the particular microbes were variable from brew to brew, so some batches were more beneficial than others.

So kombucha definitely has potential to be a good probiotic, but to get the best chance of having a variety of beneficial bacteria, it is good to eat other naturally fermented foods as well.

This article was adapted from the ‘Health Claims’ chapter in my book Simply Kombucha.

Author: stacey

Stacey lives and works in the South Island of New Zealand with her husband, their 4 children, 4 hens, and a rabbit that they secretly think must have watched Monty Python's Holy Grail movie.

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